what is cataract?
A cataract is an opacity in the lens of the eye. It is a common but easily treated condition. Your own doctor should be the main source of information about cataract, and you should follow the treatment prescribe by your doctor. This article can only help you understand cataract better.
A cataract is a hazy area in the eye's lens that causes problems with your vision. The commonest cause of cataract is aging. More than half of all Indians aged 65 and above have a cataract. In the very early stages, there is no problem with the vision; later stronger light will lessen the problem caused by cataracts. After a certain point, however, surgery is the only option to improve vision. Today, cataract surgery is one of the most safe and effective surgical procedure.
The lens is that part of the eye that helps focus light onto the retina, the light-sensitive layer that converts light to electric signals and sends these to the brain. The lens is located just behind the iris, the coloured part of the eye. The lens is made mostly of water and protein. The protein is arranged to let light pass through and focus on the retina. Sometimes some of the protein clumps together and starts to cloud a small area of the lens. This is a cataract. Over time, the cataract may become larger and cloud more of the lens, making it hard to see. Although researchers are learning more about cataracts, no one knows for sure what causes them. Scientists think there may be several causes, including smoking and diabetes. Or, it may be that the protein in the lens just changes as it ages. There is also some evidence that cataracts are linked to certain vitamins and minerals. Scientists do know that a cataract won't spread from one eye to the other, although many people develop cataracts in both eyes.
Age-related cataract: Most cataracts are related to aging.
Congenital cataract: Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may not affect vision. If they do, they may need to be removed.
Secondary cataract: Cataracts are more likely to develop in people who have certain other health problems, such as diabetes.
Steroid use. Cataracts are sometimes linked to steroid use.
Traumatic cataract: Cataracts can develop soon after an eye injury, or years later.
The most common symptoms of a cataract are:
However these symptoms can also be a
sign of other eye problems. If you have any of these
symptoms, consult your eye doctor.
To detect a cataract, the lens needs to be examined. A comprehensive eye examination usually includes:
Visual acuity test: This eye chart test measures how well you see at various distances.
Pupil dilation: The pupil is widened with eye drops to allow the eye doctor to see more of the retina and look for other eye problems.
Tonometry: This is a standard test to measure fluid pressure inside the eye. Increased pressure may be a sign of glaucoma.
In early cataract, new glasses, or stronger lighting may improve vision. Once cataract is advanced surgery is the only effective.
The surgeon removes the cloudy lens and replaces it with a substitute lens. A cataract needs to be removed only if it affects your vision so much that it interferes with your daily activities. You make that decision. If you have cataracts in both eyes, the surgeon will not remove them both at the same time. You will need to have each done separately. Sometimes, a cataract should be removed even if it doesn't bother you. For example, if it prevents examination or treatment of another eye problem such as age-related macular degeneration or diabetic retinopathy, a cataract should be treated.
If you've chosen to have surgery, it's helpful to know more about it. This section describes the types of cataract surgery, lens substitutes, and what you can expect before and after surgery.
Is surgery effective? Cataract removal is one of the most common operations performed in India today. It is also one of the safest and most effective. More than 90 percent of people who have cataract surgery have better vision afterward. However, even with the best results, your vision may not be as good as before the cataract.
How is a cataract removed? The lens is enclosed in a capsule, an outer covering that holds it in place. There are many different techniques for cataract surgery, but all fall into one of two basic categories:
Intra capsular surgery: The entire lens is removed, including the capsule. Although extra capsular surgery has largely replaced this technique in the United States, it is safe and effective and may be used in some cases, for example, if the lens is too hard for phaco.
Currently, lasers cannot be used to remove a cataract. Although scientists are working on ways to use lasers in cataract surgery, these techniques are still being studied.
Before surgery, your eye doctor will order some tests. These may include tests to measure the curve of the cornea and the shape of the eye. For patients who will receive an IOL, this information helps the eye doctor choose the right type of IOL. Other tests may help to determine the health of the retina and to guide the surgery. Many people choose to stay awake during surgery, while others may need to be put to sleep for a short time. If you are awake, you'll have drugs to relax you and to numb the nerves and keep the eye from moving.
After cataract surgery, most people can go home the same day. Others may have some minor problems, such as bleeding, and may need to stay in the hospital overnight or for a few days. It's normal to feel itching, sticky eyelids, and mild discomfort for a while after cataract surgery. Some fluid discharge is also common. In most cases, healing will take about 6 weeks. After 1-2 days, even moderate discomfort should disappear. After surgery, your eye care professional will schedule exams to check on your progress. You may need to use eye drops to help healing or to prevent infection or inflammation. Ask your doctor how to use them, when to take them, and what effects they can have. Problems after surgery are rare, but they can occur. These can include infection, bleeding, higher pressure inside the eye, inflammation (pain, redness, swelling), and detachment of the retina. With prompt medical attention, these problems can be treated. Certain symptoms could mean that you need prompt treatment. If you have any of the following symptoms, call your eye care professional immediately: unusual pain, loss of vision, or flashing lights.
The lens is important for focusing. When it's removed, it usually needs to be replaced. There are three types of substitute lenses: an intraocular lens (IOL), a contact lens, or cataract glasses. Today, about 90 percent of patients choose an IOL. Of them, about 90 percent achieve 6/9 vision or better.
Intraocular lens. An IOL is a clear, plastic lens that is placed in your eye during cataract surgery. It requires no care. With an IOL, you'll have better vision and won't feel or see the new lens. A few people cannot have an IOL because their eye structure isn't suitable, or they have certain other eye diseases.
Contact lens. Most people who do not have an IOL wear soft contact lenses. Extended-wear lenses are helpful if you have trouble putting in and taking out contacts.
Cataract glasses. Some people don't want to use contact lenses or their eyes are too sensitive to wear them. For these people, cataract glasses may be the best choice. Cataract glasses affect vision differently than regular eyeglasses. Their powerful magnification (20-35 percent) may make it harder for you to judge distance and may distort your side vision. Until you've adjusted to these changes, you will need to be careful when you drive or do other activities.
After the surgery, you can read and watch TV almost right away, but your vision may be blurry. The healing eye needs time to adjust so that it can focus properly with the other eye- especially if the other eye has a cataract. This healing period may take many weeks. Your eye doctor can suggest ways to improve your vision during this time. How long it will be before you can see normally depends on the vision in your other eye, the lens substitute you choose, and your vision before surgery. With an IOL, for example, you may notice that colours have a blue tinge, and that after you've been in bright sunlight, everything is reddish for a few hours. It doesn't take long to adjust to these changes.
Sometimes people who have extra capsular surgery develop an after-cataract. When this happens, the back part of the lens capsule left in the eye becomes cloudy and keeps light from reaching the retina. Unlike a cataract, an after-cataract is treated with a laser. In a technique called YAG capsulotomy, your doctor uses a laser beam to make a tiny hole in the capsule to let light pass through. This is a painless outpatient procedure.
Although we don't know how to protect against cataracts, people over the age of 60 are at risk for many vision problems. If you are age 60 or older, you should have an eye examination through dilated pupils. This kind of exam allows your eye care professional to check for signs of age-related macular degeneration, glaucoma, cataracts, and other vision disorders.
Eye diseases should always be taken seriously. Once a diagnosis of cataract has been made, there is no emergency in having it operated. However treatment should not be unduly delayed.
Last revised: May 11, 2000